Trying to Tune my ThermoQuad

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64ragtop

64ragtop

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I dumped the Eddy 1406 and adaptor and put a fresh ThermoQuad from DemonSizzler on the late '70's manifold on my 318. Those Great BIG holes in the mani were just crying for the Great BIG TQ secondaries. The challenge now is initial setup/tuning of the TQ.

First assembly, without any gasket sealer, and I had a whistle that reminded me of the Bosun's Pipe from when I was in the Navy. I know that's a pretty certain indication of a vacuum leak, so I slathered a thin. but even coat of Permatex on both sides of the gasket, and snugged the nuts down on the studs. Got just a tiny bit of sealant squeezed out all around the carb, so that should indicate a good seal, I think. But still have the whistle. Other symptoms are an intermittant change in idle speed about once per second and adjusting the idle mixture screws doesn't seem to make much difference. I can set the idle speed up to keep the engine running, but it wants about 1100rpm.

I'm guessing that I'm just gonna have to find that whistle before I can expect to get the kind of response I expect from the idle mixture screws and can reset the idle to something more reasonable.

Any tips about just how to find vacuum leaks would be deeply appreciated!

Thanks in advance!
 
dusterdon said:
spray carb cleaner around the carb. when the idle changes you've found the leak.
Click to expand...

That's worked for me before, Don, but this TQ is being stubborn. Anyone got any other tricks that have worked for them. When this thing gets past the bog off idle, it goes like a scalded a** ape. The big secondaries moan and it's a like a whole different car. Now if it would just idle and run smooth through the low speed circuit.......

BC
 
First find the leak. Also, a whistle can come from the primary side as well.

If the carb doesn't idle down and adjust RPM wise with the screws, your running to rich.

Idle screw counterclockwise out to lower the idle untill it almost wants to stall, adjust the 2 screws upfront for higest RPM, turn idle up to what it is to be, 750 rpm or what ever.... re-turn the 2 idle screws and leave it be.

The intermintent rise and fall could be the ignition. Stock style systems have a high misfire rate vs other systems.
 
If all of the above doesn't solve the problem. Try dropping the Eddy back on and see if it solves the problem. Did you require the Permatex when you had the Eddy on there? Take a straight edge to the the base of the Thermoquad and check for warpage. I can't think of anything else except the carb itself.
 
Still having problems? What did you do so far?
 
Been prepping for a holiday weekend trip. Wanted to take (and show off) the ragtop. Maybe the whole darn problem is based on the wanting to show off???
Right now I'm just glad I have the Dakota - and miles to go before I sleep.
 
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